Latest v3.0.0 rc4 fixes (#2490)

* Use the same font size for code blocks as we do for the rest of the chat text.

* Add a conversation tray after discussion with Vincent and Andriy and gathering
of feedback from some other users. This adds the reset context back as a
recycle button and copy chat features back to the app for v3.0.0.

Signed-off-by: Adam Treat <treat.adam@gmail.com>

gpt4all-chat/qml/Theme.qml

@@ -518,7 +518,7 @@ QtObject {
             case "Dark":
                 return accentColor;
             default:
-                return accentColor;
+                return black;
         }
     }
 
@@ -529,7 +529,7 @@ QtObject {
             case "Dark":
                 return darkwhite;
             default:
-                return black;
+                return accentColor;
         }
     }
 
@@ -740,7 +740,7 @@ QtObject {
             case "Dark":
                 return green400;
             default:
-                return green400;
+                return black;
         }
     }